A Theoretical Insight into Enhanced Catalytic Activity of Au by Multiple Twin Nanoparticles

Kyoichi Sawabe,Junya Ohyama,Atsushi Satsuma,Taiki Koketsu

doi:10.3390/catal7060191

Kyoichi Sawabe, Junya Ohyama + Show 2 more

Open Access

https://doi.org/10.3390/catal7060191

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Journal: Catalysts	Publication Date: Jun 19, 2017
Citations: 5	License type: CC BY 4.0

Affiliation: Nagoya University, Kyoto University

Abstract

Recently, it has been reported that the morphology of Au nanoparticles (NPs) affects the catalytic activity of CO oxidation; twin crystal NPs show higher activity for CO oxidation than single-crystal NPs. In this study, density functional calculations have been carried out to investigate the morphology effect of Au NPs using CO as a probe molecule. In the case of Au NPs with a size of more than 2 nm, CO adsorption energy on the Au NPs is mainly determined by a coordination number (CN) of adsorption sites. CO binding to a multiple twin NP with a size of about 1 nm is stronger than that on a single-crystal NP with the same size. A simple CN explanation cannot be applied to the enhancement of CO binding to the small multiple twin NP. This enhancement is related to a deformation of the NP structure before and after CO adsorption. It is suggested that the multiple twin NP with a size of less than 1 nm, which shows the deformation upon CO adsorption, contributes to the higher activity for CO oxidation.

Highlights

It is well known that gold nanoparticles (NPs) show high catalytic activity for CO oxidation at low temperature [1,2,3]
The catalytic activity is affected by the size of Au NPs and abruptly increases as its size decreases to less than 3 nm
The size effect is sometimes explained by the reactivity in terms of special reaction sites at the metal–support interface [2,4]

Summary

Introduction

It is well known that gold nanoparticles (NPs) show high catalytic activity for CO oxidation at low temperature [1,2,3]. The size effect is sometimes explained by the reactivity in terms of special reaction sites at the metal–support interface [2,4]. There is another explanation for the size effect [5,6,7]. The percentage of highly-uncoordinated gold atoms on the Au NP surface yields observed differences in the reactivity of Au NPs. Other than the size, the morphology of Au NPs influences their catalysis [8,9,10,11,12,13,14,15,16]. The morphology, which determines the number of coordination sites available, such as corners and edges, is important for the catalytic activity

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Conclusion